This paper proposes a new type of hybrid manipulator that can be of extensive use in industries where translational motion is required while maintaining an arbitrary end-effector orientation. It consists of two serially connected parallel mechanisms, each having three degrees of freedom, of which the upper platform performs a pure translational motion with respect to the mid-platform. Closed-form forward and inverse kinematic analysis of the proposed manipulator has been carried out. It is followed by the determination of all of its singular configurations. The theoretical results have been verified numerically, and the 3D modeling and simulation of the manipulator have also been performed. A simple optimal design is presented based on optimizing the kinematic manipulability, which further demonstrates the potential of the proposed hybrid manipulator.

In this paper, we revisit the 3-degrees of freedom (DOF) pure translational mechanism. The mathematical model and the design considerations are discussed. A detailed sensitivity and error analysis is carried out and the results are discussed in a new perspective. The feasibility of the practical 3-DOF pure translational mechanism is established with novel design considerations to take care of theoretical mobility and geometrical constraints. We describe and validate the theoretical observations with stage-wise prototype models and experiments. The experimental results concur that all is well with 3-UPU in contrast to what is presented in refs. [6, 9, 10].